CN114360454B - Light-emitting unit control circuit, method, array substrate and display panel - Google Patents
Light-emitting unit control circuit, method, array substrate and display panel Download PDFInfo
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Abstract
The invention discloses a light-emitting unit control circuit, a light-emitting unit control method, an array substrate and a display panel, wherein the light-emitting unit control circuit comprises: a pre-charge source connected to the gate of the second thin film transistor or the light emitting cell; when receiving a pre-charging signal output by the front-end control chip, the pre-charging power supply regulates the voltage of the grid electrode of the second thin film transistor or the light-emitting unit to a pre-charging voltage; when receiving the driving signal output by the front-end control chip, the driving circuit adjusts the gate of the second thin film transistor or the pre-charging voltage of the light-emitting unit to a target voltage. According to the invention, the grid electrode of the second thin film transistor or the light-emitting unit is pre-charged, so that the current change rate in the second thin film transistor or the light-emitting unit is reduced when the light-emitting unit is driven, and the technical problem that the organic light-emitting diode has gray-scale ghost shadow is solved.
Description
Technical Field
The invention relates to the technical field of display, in particular to a light-emitting unit control circuit, a light-emitting unit control method, an array substrate and a display panel.
Background
Organic light emitting display diodes have been increasingly used in high performance displays as a current type light emitting device. Compared with the LCD, the LCD has the advantages of high contrast, super lightness and thinness, flexibility and the like due to the self-luminous characteristic.
However, brightness uniformity and ghosting are two major challenges it currently faces. One of the important reasons for the poor uniformity of the brightness of the OLED and the image sticking problem is the hysteresis characteristic of the ingan semiconductor, and the current passing through the tft is not the same when the tft scans in the forward direction and the reverse direction. For example, in the scanning process, two different gray scale changing processes of L255 → L127 and L0 → L127 appear on the panel of the light emitting display diode, the thin film transistor will have forward and reverse scanning conditions, and at this time, the currents of the light emitting display diode are different, which directly causes the L127 gray scale to have residual shadow.
The above is only for the purpose of assisting understanding of the technical solution of the present invention, and does not represent an admission that the above is the prior art.
Content of application
The invention mainly aims to provide a light-emitting unit control circuit, a light-emitting unit control method, an array substrate and a display panel, and aims to solve the technical problem that gray-scale ghost shadow occurs in an organic light-emitting diode.
In order to solve the above technical problem, the present invention provides a light emitting unit control circuit, where the light emitting unit control circuit includes a driving circuit, the driving circuit is connected to a front end control chip and a light emitting unit, the driving circuit includes a first thin film transistor and a second thin film transistor, and the light emitting unit control circuit further includes: a pre-charge source connected to the gate of the second thin film transistor or the light emitting unit;
the pre-charging power supply is used for adjusting the voltage of the grid electrode of the second thin film transistor or the light-emitting unit to a pre-charging voltage when receiving a pre-charging signal output by the front-end control chip;
and the driving circuit is used for adjusting the grid electrode of the second thin film transistor or the pre-charging voltage of the light-emitting unit to a target voltage when receiving the driving signal output by the front-end control chip.
Optionally, the light emitting unit control circuit further comprises: a third thin film transistor;
the grid electrode of the third thin film transistor is connected with the front-end control chip, the drain electrode of the third thin film transistor is connected with the pre-charging source, and the source electrode of the third thin film transistor is connected with the grid electrode of the second thin film transistor or the light-emitting unit.
Optionally, the source of the third thin film transistor is connected to the gate of the second thin film transistor and the light emitting unit.
Optionally, the light emitting unit control circuit further comprises: a third thin film transistor and a fourth thin film transistor;
the grid electrode of the third thin film transistor is connected with the front-end control chip, the drain electrode of the third thin film transistor is connected with the pre-charging source, and the source electrode of the third thin film transistor is connected with the grid electrode of the second thin film transistor; the grid electrode of the fourth thin film transistor is connected with the front-end control chip, the drain electrode of the fourth thin film transistor is connected with the pre-charging source, and the source electrode of the fourth thin film transistor is connected with the light-emitting unit.
Optionally, the light emitting unit control circuit further comprises: a fifth thin film transistor;
the grid electrode of the fifth thin film transistor is connected with the front-end control chip, the drain electrode of the fifth thin film transistor is connected with the source electrode of the second thin film transistor, and the source electrode of the fifth thin film transistor is connected with the front-end control chip.
In addition, to achieve the above object, the present invention also provides a light emitting unit control method based on a light emitting unit control circuit, the light emitting unit control method comprising:
when a pre-charging signal output by the front-end control chip is received, adjusting the voltage of the grid electrode of the second thin film transistor or the light-emitting unit to a pre-charging voltage;
and when receiving a driving signal output by the front-end control chip, adjusting the grid electrode of the second thin film transistor or the pre-charging voltage of the light-emitting unit to a target voltage.
Optionally, the step of adjusting the voltage of the gate of the second thin film transistor or the light emitting unit to a pre-charge voltage when receiving the pre-charge signal output by the front end control chip includes:
when a pre-charge signal output by the front-end control chip is received, a first loop between the pre-charge power supply and the grid electrode of the second thin film transistor or a second loop between the pre-charge power supply and the light-emitting unit is conducted;
when the first loop circuit is conducted, the voltage of the grid electrode of the second thin film transistor is adjusted to a pre-charging voltage;
and when the second loop is conducted, adjusting the voltage of the light-emitting unit to a pre-charging voltage.
Optionally, before the step of adjusting the voltage of the gate of the second thin film transistor to the precharge voltage when the first loop is turned on, the method further includes:
and when a pre-charge signal output by the front-end control chip is received, a first loop between the pre-charge source and the grid electrode of the second thin film transistor and a second loop between the pre-charge source and the light-emitting unit are conducted.
In addition, to achieve the above object, the present invention also provides an array substrate, including: a light emitting unit and the light emitting unit control circuit.
In addition, in order to achieve the above object, the present invention further provides a display panel, where the display panel includes a light emitting layer, an encapsulation layer, and the array substrate, and the light emitting layer is located between the array substrate and the encapsulation layer.
The invention provides a light-emitting unit control circuit, a method, an array substrate and a display panel, wherein the light-emitting unit control circuit comprises a driving circuit, the driving circuit is respectively connected with a front-end control chip and a light-emitting unit, the driving circuit comprises a first thin film transistor and a second thin film transistor, and the light-emitting unit control circuit further comprises: a pre-charge source connected to the gate of the second thin film transistor or the light emitting unit; the pre-charging power supply is used for adjusting the voltage of the grid electrode of the second thin film transistor or the light-emitting unit to a pre-charging voltage when receiving a pre-charging signal output by the front-end control chip; and the driving circuit is used for adjusting the grid electrode of the second thin film transistor or the pre-charging voltage of the light-emitting unit to a target voltage when receiving the driving signal output by the front-end control chip. According to the invention, the grid electrode of the second thin film transistor or the light-emitting unit is pre-charged, so that the current change rate in the second thin film transistor or the light-emitting unit is reduced when the light-emitting unit is driven, and the technical problem that the organic light-emitting diode has gray-scale ghost shadow is solved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the description below are only the first embodiment, the second embodiment, and the third embodiment of the array substrate of the present invention, the embodiment of the display panel, and the corresponding drawings of the embodiment of the display, and for those skilled in the art, other drawings can be obtained according to the structures shown in these drawings without creative efforts.
FIG. 1 is a diagram of the variation of the current through the TFT in the forward scanning and reverse scanning directions due to the hysteresis effect of the TFT;
FIG. 2 is a first circuit structure diagram of a light-emitting unit control circuit according to a first embodiment of the present invention;
FIG. 3 is a second circuit structure diagram of a light-emitting unit control circuit according to a first embodiment of the present invention;
FIG. 4 is a first circuit structure diagram of a second embodiment of a light-emitting unit control circuit according to the present invention;
FIG. 5 is a second circuit diagram of a light-emitting unit control circuit according to a second embodiment of the present invention;
FIG. 6 is a timing diagram of a second embodiment of the light-emitting unit control circuit according to the present invention;
FIG. 7 is a third circuit structure diagram of a second embodiment of a light-emitting unit control circuit according to the present invention;
FIG. 8 is a first circuit structure diagram of a third embodiment of a control circuit of a light emitting unit according to the present invention;
FIG. 9 is a diagram of a fourth embodiment of a light-emitting unit control circuit according to the present invention;
FIG. 10 is a diagram illustrating a second circuit structure of a fourth embodiment of a control circuit of a light emitting unit according to the present invention;
FIG. 11 is a flowchart illustrating a method for controlling a light-emitting unit according to a first embodiment of the present invention;
FIG. 12 is a flowchart illustrating a second method for controlling a light-emitting unit according to an embodiment of the present invention;
FIG. 13 is a flowchart illustrating a third method for controlling a light-emitting unit according to an embodiment of the present invention;
fig. 14 is a schematic structural diagram of a display panel according to an embodiment of the present application.
The reference numbers illustrate:
| reference numerals | Name (R) | Reference numerals | Name (R) | |
| Vdata | Scanning voltage | Vref | Pre-charging power supply | |
| Scan1 | Pre-charge signal | PVEE | Ground connection | |
| Scan2 | Drive signal | T1～T5 | First to fifth thin film transistors | |
| | Driving voltage | 10 | Driving circuit | |
| D1 | A first organic |
20 | Array substrate | |
| C1～C2 | First to |
30 | |
|
| 40 | Encapsulation layer |
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention.
Referring to fig. 1, 2 and 3, fig. 1 is a diagram illustrating a variation of a current passing through a tft in a forward scanning direction and a reverse scanning direction due to a hysteresis effect of the tft, fig. 2 is a first circuit configuration diagram of a light emitting unit control circuit according to a first embodiment of the light emitting unit control circuit of the present invention, and fig. 3 is a second circuit configuration diagram of the light emitting unit control circuit according to a first embodiment of the light emitting unit control circuit of the present invention.
In this embodiment, the light emitting unit control circuit includes a driving circuit 10, the driving circuit is connected to the front end control chip and the light emitting unit, the driving circuit 10 includes a first thin film transistor T1 and a second thin film transistor T2, and the light emitting unit control circuit further includes: and a precharge power Vref connected to the gate of the second thin film transistor T2 or the light emitting cell.
It should be understood that during the scanning of the pixel, it is likely that both ends are scanned simultaneously, for example, one end is scanned from a gray scale value of 255, the other end is scanned from a gray scale value of 0, and the scanning process is finally ended at a gray scale value of 127. In the process of simultaneous scanning at two ends, the currents in the second thin film transistors T2 in the driving circuit for driving the light emitting unit are different, and the light emitting unit is directly subjected to afterimage due to excessive current change in the second thin film transistors or excessive current change in the light emitting unit in a short time. Referring to fig. 1, since the tft has a certain hysteresis effect, the current passing through the tft varies in the forward and reverse directions, and the current passing through the tft varies directly from the current value at the previous time to the current value at the next time, which causes an excessive variation of the current value in a short time and causes image sticking.
Note that the precharge power source Vref is a power source for maintaining the gate of the second thin film transistor T2 or the input terminal of the light emitting unit at a constant voltage value. In the gray scale changing process, the initial gray scale value corresponds to an initial voltage, and the target gray scale value corresponds to a target voltage. The precharge voltage provided by the precharge power source Vref is within a range between the initial voltage and the target voltage. The precharge voltage provided by the precharge power supply Vref may be set according to a range of gray-scale value variation. For example, when the gray scale value changes from 255 to 127, the precharge voltage should be between the initial voltage value corresponding to 255 and the target voltage value corresponding to 127. The pre-charge voltage provided by the pre-charge power Vref does not change the operation state of the second thin film transistor T2 and the light emitting unit, that is, the operation state of the second thin film transistor T2 changes according to the scan voltage Vdata, and the operation state of the light emitting unit changes according to the driving voltage PVDD. The front-end control chip is a chip for controlling a driving process of the light emitting unit, and the front-end control chip may be a chip having the same function, such as a one-chip microcomputer chip or an ARM chip. In this embodiment, the front-end control chip is a chip in the prior art and is not shown in the drawings of the specification. In this embodiment, the light emitting unit is composed of the first organic light emitting diode D1, the second capacitor C2 and other related components, and the connection of other components is not specifically limited herein.
Referring to fig. 2, it can be understood that, when there is a change in the current flowing through the second thin film transistor T2 or the current input to the light emitting cell, the gate voltage of the second thin film transistor T2 or the voltage at the input terminal of the light emitting cell is changed from the pre-charge voltage of the pre-charge power to the target voltage value, thereby reducing the rate of change of the current flowing through the thin film transistor T2 or the rate of change of the current input to the light emitting cell. For example, in the process of adjusting the gray-scale value of one light emitting unit from 0 to 127, the gate voltage of the second thin film transistor T2 in the prior art is directly adjusted from the voltage value corresponding to the gray-scale value 0 to the voltage value corresponding to the gray-scale value 127, and the gate voltage is changed back to cause a larger current change rate in the second thin film transistor T2, which results in the occurrence of image sticking. In the present embodiment, the gate voltage of the second thin film transistor T2 is adjusted to a voltage corresponding to the gray level 127 from the precharge voltage provided by the precharge voltage source Vref, so as to reduce the current variation rate passing through the second thin film transistor T2. Referring to fig. 3, a voltage input to an input terminal of a light emitting cell is precharged in fig. 3. The specific process of adjusting the current change rate of the input light emitting unit in fig. 3 can refer to the process of adjusting the second thin film transistor T2 in fig. 2, and is not described herein again.
In a specific implementation, the precharge power source Vref may adjust a voltage of the gate of the second thin film transistor T2 or the light emitting unit to a precharge voltage when receiving a precharge signal output by the front end control chip, where the precharge signal is sent before a driving signal of the light emitting unit. Of course, in this embodiment, the precharge voltage Vref may be continuously provided to the gate of the second thin film transistor T2 or the light emitting unit, so that the gate of the second thin film transistor T2 or the input terminal of the light emitting unit is always kept at the precharge voltage state. Referring to fig. 2, in a specific driving process, the front-end control chip may output a driving signal Scan2 to a gate of a first thin film transistor T1 in the driving circuit, so as to control the first thin film transistor T1 to be turned on, at this time, the scanning signal Vdata may provide a certain target voltage to the gate of the second thin film transistor T2 through the first thin film transistor T1 in the driving circuit, and at this time, a precharge voltage already exists on the gate of the second thin film transistor T2, so as to adjust the gate of the second thin film transistor T2 to the target voltage. When the second thin film transistor T2 is turned on, the driving power supply may drive the light emitting cell by outputting the driving voltage PVDD. Referring to fig. 3, in the driving process in fig. 3, the front end control chip may output a driving signal Scan2 to a gate of a first thin film transistor T1 in the driving circuit to control the first thin film transistor T1 to be turned on, at this time, the scanning signal Vdata may provide a certain target voltage to the gate of the second thin film transistor T2 through the first thin film transistor T1 in the driving circuit to turn on the second thin film transistor T2, the driving power source may drive the light emitting unit by outputting the driving voltage PVDD, and at this time, the input terminal of the light emitting unit already has the precharge voltage, so as to adjust the preset voltage at the input terminal of the light emitting unit to the driving voltage PVDD.
In a first embodiment of the light emitting unit control circuit, the light emitting unit control circuit includes a driving circuit, the driving circuit is respectively connected to the front end control chip and the light emitting unit, the driving circuit includes a first thin film transistor and a second thin film transistor, and the light emitting unit control circuit further includes: a pre-charge source connected to the gate of the second thin film transistor or the light emitting unit; the pre-charging power supply is used for adjusting the voltage of the grid electrode of the second thin film transistor or the light-emitting unit to a pre-charging voltage when receiving a pre-charging signal output by the front-end control chip; and the driving circuit is used for adjusting the grid electrode of the second thin film transistor or the pre-charging voltage of the light-emitting unit to a target voltage when receiving the driving signal output by the front-end control chip. In the first embodiment, the gate of the second thin film transistor or the light emitting unit is precharged, so that the current change rate in the second thin film transistor or the light emitting unit is reduced when the light emitting unit is driven, and the technical problem that gray-scale ghost occurs in the light emitting unit is solved.
Fig. 4 and fig. 5 are diagrams showing a second embodiment of the light-emitting unit control circuit according to the present invention, where fig. 4 is a first circuit configuration diagram of the light-emitting unit control circuit according to the second embodiment of the light-emitting unit control circuit according to the present invention, and fig. 5 is a second circuit configuration diagram of the light-emitting unit control circuit according to the second embodiment of the light-emitting unit control circuit according to the present invention.
In this embodiment, the light emitting unit control circuit further includes: a third thin film transistor T3;
the grid electrode of the third thin film transistor T3 is connected with the front end control chip, the drain electrode of the third thin film transistor T3 is connected with the pre-charging source Vref, and the source electrode of the third thin film transistor T3 is connected with the grid electrode of the second thin film transistor T2 or the light-emitting unit.
It should be noted that in the present embodiment, the third thin film transistor T3 controls the connection between the precharge power source Vref and the gate of the second thin film transistor T2 or the light emitting unit. The third thin film transistor T3 is mainly used for turning on and off a loop function between the precharge power Vref and the gate or the light emitting unit of the second thin film transistor T2 according to the precharge signal Scan1 output by the front end control chip, and other power transistors having the same function are also applicable, for example, an MOS transistor, a triode, an IGBT, and the like may be adopted, and the details are not limited herein.
It should be understood that when the light emitting cell does not need to be driven for a short time, the precharge voltage is always output to the gate of the second thin film transistor T2 or the light emitting cell by the precharge voltage Vref, which causes a large amount of waste of resources. Therefore, it is only necessary to provide a predetermined voltage to the gate electrode of the second thin film transistor T2 or the light emitting cell before driving the light emitting cell.
Referring to fig. 4 and 6, the front end control chip may output a precharge signal Scan1 to the gate of the third thin film transistor T3 before driving the light emitting unit, thereby turning on the third thin film transistor T3, and the precharge voltage Vref may provide a precharge voltage to the gate of the second thin film transistor T2. When the grid electrode of the second thin film transistor T2 reaches the pre-charging voltage, the front end control chip outputs a driving signal Scan2 to the grid electrode of the first thin film transistor T1 to drive the light-emitting unit. Referring to fig. 5, similarly, the front end control chip may output the precharge signal Scan1 to the gate of the third thin film transistor T3 before driving the light emitting unit, so as to turn on the third thin film transistor T3, and the precharge voltage Vref may provide a precharge voltage for the output terminal of the light emitting unit. When the input end of the light-emitting unit reaches the pre-charging voltage, the front-end control chip outputs a driving signal Scan2 to the grid electrode of the first thin film transistor T1 to drive the light-emitting unit.
Referring to fig. 7, in this embodiment, the front-end control chip may also control the first loop and the second loop at the same time, and may directly use a third thin film transistor T3, and connect the source of the third thin film transistor T3 with the gate of the second thin film transistor T2 and the light emitting unit at the same time. When the front end control chip outputs a precharge signal Scan1, the third thin film transistor T3 is turned on, and the precharge voltage Vref may simultaneously provide a precharge voltage to the gate of the second thin film transistor T2 and the input terminal of the light emitting unit.
In the second embodiment of the light emitting unit control circuit, the third thin film transistor T3 is arranged to control the first loop between the preset power Vref and the gate of the second thin film transistor T2 or the second loop between the preset power Vref and the light emitting unit; when the first loop is conducted, a preset power supply Vref provides a precharge voltage for the grid electrode of the second thin film transistor T2; when the second loop is turned on, the preset power Vref provides a precharge voltage for the input terminal of the light emitting unit. In the second embodiment, the pre-charge power Vref can be reduced to effectively avoid resource waste under the condition of more accurately eliminating the gray-scale image sticking of the light emitting unit.
Referring to fig. 8, fig. 8 is a first circuit structure diagram of a light emitting unit control circuit according to a third embodiment of the present invention; a third embodiment of the control circuit for a light emitting unit of the present invention is provided; based on the above embodiment, a third embodiment of the array substrate of the present invention is provided.
In an embodiment three, the light emitting unit control circuit further includes: a third thin film transistor T3 and a fourth thin film transistor T4;
the grid electrode of the third thin film transistor T3 is connected with the front-end control chip, the drain electrode of the third thin film transistor T3 is connected with the pre-charge power supply Vref, and the source electrode of the third thin film transistor T3 is connected with the grid electrode of the second thin film transistor T2; the grid electrode of the fourth thin film transistor T4 is connected with the front end control chip, the drain electrode of the fourth thin film transistor T4 is connected with the pre-charge power source Vref, and the source electrode of the fourth thin film transistor T4 is connected with the light emitting unit.
It should be noted that the third thin film transistor T3 and the fourth thin film transistor T4 may be replaced by other power transistors having the same function, such as a triode, a MOS transistor, and an IGBT. The third thin film transistor T3 is used for controlling the on/off of the first loop between the precharge power source Vref and the gate of the second thin film transistor T2. The fourth thin film transistor T4 is used for controlling the on/off of the second loop between the precharge power source Vref and the light emitting unit.
In the present embodiment, the first loop between the second thin film transistor T2 and the precharge power source Vref and the second loop between the precharge power source Vref and the flash unit can be respectively matched by providing the third thin film transistor T3 and the fourth thin film transistor T4. The front-end control chip can output a pre-charging signal Scan1 to the gate of any one of the third thin film transistor T3 and the fourth thin film transistor T4 to independently control one loop; the front-end control chip can also simultaneously output two precharge signals Scan1 to the gates of the third thin film transistor T3 and the fourth thin film transistor T4, and simultaneously control two loops.
In the third embodiment of the light emitting cell control circuit, the first loop between the pre-charge power Vref and the gate of the second thin film transistor T2 and the second loop between the pre-charge power Vref and the light emitting cell can be simultaneously paired by providing the third thin film transistor T3 and the fourth thin film transistor T4. In the third embodiment, one of the first loop and the second loop may be controlled separately, or two loops may be controlled simultaneously, and the problem of image sticking occurring in the light emitting unit may be solved more accurately under the condition of controlling the two loops simultaneously.
Fig. 9 and fig. 10 are views showing a fourth embodiment of the light emitting unit control circuit according to the present invention, and fig. 9 is a first circuit configuration diagram of the light emitting unit control circuit according to the fourth embodiment of the light emitting unit control circuit according to the present invention; fig. 10 is a second circuit configuration diagram of a light-emitting unit control circuit according to a fourth embodiment of the light-emitting unit control circuit of the present invention.
In this embodiment, the light emitting unit control circuit further includes: a fifth thin film transistor T5;
the grid electrode of the fifth thin film transistor T5 is connected with the front end control chip, the drain electrode of the fifth thin film transistor T5 is connected with the source electrode of the second thin film transistor T2, and the source electrode of the fifth thin film transistor T5 is connected with the front end control chip.
It is understood that the light emitting unit may gradually decrease in brightness with an increase in lighting time, resulting in the light emitting unit having insufficient brightness, in which case the driving current or driving voltage for driving the light emitting unit needs to be compensated. The fifth thin film transistor T5 is a transistor for collecting the driving current supplied from the driving power supply PVDD. When the fifth thin film transistor T5 is turned on, the front end control chip may collect the driving current and compensate the luminance of the light emitting unit according to the driving current.
It should be noted that other power transistors having control terminals may be used instead of the fifth thin film transistor T5. The fifth thin film transistor T5 is connected in series with the second thin film transistor T2, and the fifth thin film transistor T5 is located between the driving power source PVDD and the light emitting unit.
In a specific implementation, the front-end control chip may output the acquisition signal to a gate of the fifth thin film transistor T5 to control the fifth thin film transistor T5 to be turned on, and when the fifth thin film transistor T5 is turned on, the front-end control chip may acquire the driving current of the light emitting unit, and when the driving current is lower than the rated driving current, output a corresponding compensation signal to control the driving power supply PVDD to output a higher driving current to compensate the brightness of the light emitting unit.
In a fourth embodiment of the light emitting unit control circuit, the fifth thin film transistor T5 is provided on the basis of the first embodiment to collect the driving current, and the luminance of the light emitting unit is compensated when the driving current does not satisfy the rated driving current. In the fifth embodiment, under the condition that the afterimage of the light emitting unit can be accurately obtained, the luminance of the light emitting unit can be effectively compensated.
Referring to fig. 11, fig. 11 is a flowchart illustrating a method for controlling a light emitting unit according to a first embodiment of the present invention. Based on the disclosure of fig. 11, a first embodiment of a method for controlling a light emitting unit of the present invention is provided.
Referring to fig. 11, a light emitting unit control method in a first embodiment of the light emitting unit control method includes:
step S10: when a pre-charging signal output by the front-end control chip is received, adjusting the voltage of the grid electrode of the second thin film transistor or the light-emitting unit to a pre-charging voltage;
step S20: and when receiving the driving signal output by the front-end control chip, adjusting the grid electrode of the second thin film transistor or the pre-charging voltage of the light-emitting unit to a target voltage.
Note that the precharge power supply is a power supply for maintaining the gate of the second thin film transistor or the input terminal of the light emitting unit at a constant voltage value. In the gray scale changing process, the initial gray scale value corresponds to an initial voltage, and the target gray scale value corresponds to a target voltage. The pre-charging voltage provided by the pre-charging source is within a range of the initial voltage and the target voltage. The pre-charge voltage provided by the pre-charge source can be set according to the range of gray-scale value variation. For example, when the gray scale value changes from 255 to 127, the precharge voltage should be between the initial voltage value corresponding to 255 and the target voltage value corresponding to 127. The pre-charge voltage provided by the pre-charge power Vref does not change the operating state of the second thin film transistor and the light emitting unit, that is, the operating state of the second thin film transistor changes according to the scan voltage, and the operating state of the light emitting unit changes according to the driving voltage. The front-end control chip is a chip for controlling a driving process of the light emitting unit, and the front-end control chip may be a chip having the same function, such as a one-chip microcomputer chip or an ARM chip. In this embodiment, the front-end control chip is a chip in the prior art and is not shown in the drawings of the specification. In this embodiment, the light emitting unit is composed of the first organic light emitting diode, the second capacitor and other related components, and the connection of other components is not specifically limited herein.
It can be understood that, when a change occurs in the current flowing through the second thin film transistor or the current input to the light emitting unit, the gate voltage of the second thin film transistor or the voltage at the input terminal of the light emitting unit changes from the precharge voltage of the precharge voltage to the target voltage value, thereby reducing the rate of change of the current flowing through the thin film transistor or the rate of change of the current input to the light emitting unit. For example, in the process of adjusting the gray scale value of one light emitting unit from 0 to 127, the gate voltage of the second thin film transistor in the prior art is directly adjusted from the voltage value corresponding to the gray scale value of 0 to the voltage value corresponding to the gray scale value of 127, and the gate voltage is changed back to the voltage value corresponding to the gray scale value of 0, which causes a large current change rate in the second thin film transistor, resulting in the occurrence of the image sticking. In this embodiment, the gate voltage of the second thin film transistor is adjusted from the precharge voltage provided by the precharge source to a voltage corresponding to the gray level 127, thereby reducing the rate of change of the current through the second thin film transistor. The specific process of adjusting the current change rate input to the light emitting unit may refer to the process of adjusting the second thin film transistor, and is not described herein again.
In a specific implementation, the precharge power supply may adjust the voltage of the gate of the second thin film transistor or the light emitting unit to a precharge voltage when receiving a precharge signal output by the front end control chip, where the precharge signal is sent before a driving signal of the light emitting unit. Of course, in this embodiment, the precharge voltage may be continuously provided to the gate of the second thin film transistor or the light emitting unit by the precharge power supply, so that the gate of the second thin film transistor or the input terminal of the light emitting unit is always kept in the precharge voltage state. In the specific driving process, the front-end control chip can output a driving signal to the gate of the first thin film transistor in the driving circuit to control the first thin film transistor to be turned on, at this time, the scanning signal can provide a certain target voltage for the gate of the second thin film transistor through the first thin film transistor in the driving circuit, and at this time, the gate of the second thin film transistor is already pre-charged with voltage, so that the gate of the second thin film transistor is adjusted to the target voltage. When the second thin film transistor is turned on, the driving power supply may drive the light emitting unit by outputting the driving voltage. In the driving process, the front-end control chip can output a driving signal to a grid electrode of a first thin film transistor in the driving circuit to control the first thin film transistor to be conducted, at the moment, a scanning signal can provide a certain target voltage for the grid electrode of a second thin film transistor through the first thin film transistor in the driving circuit to conduct a second thin film transistor, the driving power supply can drive the light-emitting unit through outputting the driving voltage, at the moment, the input end of the light-emitting unit already has the pre-charging voltage, and the preset voltage of the input end of the light-emitting unit is adjusted to the driving voltage.
In a first embodiment of the light emitting unit control method, the light emitting unit control method adjusts the voltage of the gate of the second thin film transistor or the light emitting unit to a pre-charge voltage when receiving a pre-charge signal output by the front end control chip; and when receiving the driving signal output by the front-end control chip, adjusting the grid electrode of the second thin film transistor or the pre-charging voltage of the light-emitting unit to a target voltage. In the first embodiment, the gate of the second thin film transistor or the light emitting unit is precharged, so that the current change rate in the second thin film transistor or the light emitting unit is reduced when the light emitting unit is driven, and the technical problem of gray-scale ghost of the light emitting unit is solved.
Referring to fig. 12, fig. 12 is a flowchart illustrating a second method for controlling a light emitting unit according to an embodiment of the present invention. Based on the above embodiment of the light emitting unit control method, a second embodiment of the light emitting unit control method of the present invention is provided.
In a second embodiment of the method for controlling a light emitting unit, the step S101 specifically includes:
step S101: when a pre-charge signal output by the front-end control chip is received, a first loop between the pre-charge source and the grid electrode of the second thin film transistor or a second loop between the pre-charge source and the light-emitting unit is conducted;
step S102: when the first loop is conducted, adjusting the voltage of the grid electrode of the second thin film transistor to a pre-charging voltage;
step S103: and when the second loop is conducted, adjusting the voltage of the light-emitting unit to a pre-charging voltage.
It should be understood that when the light emitting cell does not need to be driven for a short time, the precharge voltage is always output to the gate of the second thin film transistor or the light emitting cell through the precharge source, which causes a large amount of resource waste. Therefore, it is only necessary to provide a predetermined voltage to the gate electrode of the second thin film transistor or the light emitting cell before driving the light emitting cell.
In a specific implementation, the front-end control chip may output a precharge signal to a gate of the third thin film transistor before driving the light emitting unit, so as to turn on the third thin film transistor, and the precharge power supply may provide a precharge voltage to the gate of the second thin film transistor. When the grid of the second thin film transistor reaches the pre-charging voltage, the front end control chip outputs a driving signal to the grid of the first thin film transistor to drive the light-emitting unit. Similarly, the front-end control chip may output a precharge signal to a gate of the third thin film transistor before driving the light emitting unit, so as to turn on the third thin film transistor, and the precharge power supply may provide a precharge voltage to the output terminal of the light emitting unit. And when the input end of the light-emitting unit reaches the pre-charging voltage, the front-end control chip outputs a driving signal to the grid electrode of the first thin film transistor to drive the light-emitting unit.
In a second embodiment of the method for controlling a light emitting unit, a third thin film transistor is arranged to control a first loop between a preset power supply and a grid electrode of a second thin film transistor or a second loop between the preset power supply and the light emitting unit; when the first loop is conducted, a preset power supply provides a pre-charging voltage for the grid electrode of the second thin film transistor; when the second loop is conducted, the preset power supply provides a pre-charging voltage for the input end of the light-emitting unit. In the second embodiment, the pre-charge power can be reduced to effectively avoid the resource waste while more accurately eliminating the gray-scale image sticking of the light-emitting unit.
Referring to fig. 13, fig. 13 is a flowchart illustrating a third method for controlling a light emitting unit according to an embodiment of the present invention. Based on the above embodiment of the light emitting unit control method, a third embodiment of the light emitting unit control method of the present invention is provided.
In a third embodiment of the light-emitting unit control method, before the step S101, the method further includes:
step S10': and when a pre-charging signal output by the front-end control chip is received, a first loop between the pre-charging source and the grid electrode of the second thin film transistor and a second loop between the pre-charging source and the light-emitting unit are conducted.
Accordingly, step S20 is step S20': and when receiving the driving signal output by the front-end control chip, adjusting the grid electrode of the second thin film transistor and the pre-charging voltage of the light-emitting unit to a target voltage.
It is to be understood that the first circuit between the second thin film transistor and the precharge source and the second circuit between the precharge source and the flash unit may be separately aligned by providing a third thin film transistor and a fourth thin film transistor. The front-end control chip can output a pre-charging signal to the grid electrode of any one of the third thin film transistor and the fourth thin film transistor and independently control one loop; the front-end control chip can also simultaneously output two pre-charging signals to the grid electrodes of the third thin film transistor and the fourth thin film transistor and simultaneously control the two loops.
In the third embodiment of the light emitting unit control method, the first loop between the precharge source and the gate of the second thin film transistor and the second loop between the precharge source and the light emitting unit can be simultaneously paired by providing the third thin film transistor and the fourth thin film transistor. In the third embodiment, one of the first loop and the second loop may be controlled separately, or two loops may be controlled simultaneously, and the problem of image sticking occurring in the light emitting unit may be solved more accurately when the two loops are controlled simultaneously.
In addition, the invention also provides an array substrate which comprises a light-emitting unit and the light-emitting unit control circuit. Since the array substrate adopts all the technical solutions of all the embodiments, at least all the beneficial effects brought by the technical solutions of the embodiments are achieved, and are not described in detail herein.
In addition, the present invention further provides a display panel, referring to fig. 14, fig. 14 is a schematic structural diagram of an embodiment of the display panel of the present application, where the display panel includes a light emitting layer 30, an encapsulation layer 40, and the array substrate 20, and the light emitting layer 30 is located between the array substrate 20 and the encapsulation layer 40.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all equivalent structures or equivalent processes performed by the present invention or directly or indirectly applied to other related technical fields are also included in the scope of the present invention.
It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that all directional indicators (such as up, down, left, right, front, and back \8230;) in the embodiments of the present invention are only used to explain the relative positional relationship between the components, the motion situation, etc. in a specific posture (as shown in the attached drawings), and if the specific posture is changed, the directional indicators are changed accordingly.
In addition, the descriptions related to "first", "second", etc. in the present invention are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions in the embodiments may be combined with each other, but must be based on the realization of the technical solutions by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the technical solutions should be considered that the combination does not exist, and the technical solutions are not within the protection scope of the present invention.
Claims (10)
1. The utility model provides a light-emitting unit control circuit, light-emitting unit control circuit includes drive circuit, drive circuit and front end control chip and light-emitting unit are connected, drive circuit includes first thin film transistor and second thin film transistor, its characterized in that, light-emitting unit control circuit still includes: a pre-charge source connected to the gate of the second thin film transistor or the light emitting unit;
the pre-charging source is used for adjusting the voltage of the grid electrode of the second thin film transistor or the light-emitting unit to a pre-charging voltage when receiving a pre-charging signal output by the front-end control chip, wherein the pre-charging voltage is within a range between the initial voltage and a target voltage of the grid electrode of the second thin film transistor or the light-emitting unit;
and the driving circuit is used for adjusting the grid electrode of the second thin film transistor or the pre-charging voltage of the light-emitting unit to a target voltage when receiving the driving signal output by the front-end control chip.
2. The light-emitting-unit control circuit according to claim 1, further comprising: a third thin film transistor;
the grid electrode of the third thin film transistor is connected with the front-end control chip, the drain electrode of the third thin film transistor is connected with the pre-charging source, and the source electrode of the third thin film transistor is connected with the grid electrode of the second thin film transistor or the light-emitting unit.
3. The light emitting cell control circuit according to claim 2, wherein a source of the third thin film transistor is connected to a gate of the second thin film transistor and the light emitting cell.
4. The light-emitting-unit control circuit according to claim 1, further comprising: a third thin film transistor and a fourth thin film transistor;
the grid electrode of the third thin film transistor is connected with the front-end control chip, the drain electrode of the third thin film transistor is connected with the pre-charging source, and the source electrode of the third thin film transistor is connected with the grid electrode of the second thin film transistor; the grid electrode of the fourth thin film transistor is connected with the front-end control chip, the drain electrode of the fourth thin film transistor is connected with the pre-charging source, and the source electrode of the fourth thin film transistor is connected with the light-emitting unit.
5. The light-emitting-unit control circuit according to claim 1, further comprising: a fifth thin film transistor;
the grid electrode of the fifth thin film transistor is connected with the front-end control chip, the drain electrode of the fifth thin film transistor is connected with the source electrode of the second thin film transistor, and the source electrode of the fifth thin film transistor is connected with the front-end control chip.
6. A light emitting unit control method based on the light emitting unit control circuit according to any one of claims 1 to 5, wherein the light emitting unit control method comprises:
when a pre-charging signal output by the front-end control chip is received, adjusting the voltage of the grid electrode of the second thin film transistor or the light-emitting unit to a pre-charging voltage, wherein the pre-charging voltage is within a range of an initial voltage and a target voltage of the grid electrode of the second thin film transistor or the light-emitting unit;
and when receiving the driving signal output by the front-end control chip, adjusting the grid electrode of the second thin film transistor or the pre-charging voltage of the light-emitting unit to a target voltage.
7. The method of claim 6, wherein the step of adjusting the voltage of the gate of the second thin film transistor or the light emitting unit to a precharge voltage upon receiving a precharge signal output from the front end control chip comprises:
when a pre-charge signal output by the front-end control chip is received, a first loop between the pre-charge source and the grid electrode of the second thin film transistor or a second loop between the pre-charge source and the light-emitting unit is conducted;
when the first loop is conducted, adjusting the voltage of the grid electrode of the second thin film transistor to a pre-charging voltage;
and when the second loop is conducted, adjusting the voltage of the light-emitting unit to a pre-charging voltage.
8. The method of controlling a light-emitting unit according to claim 7, wherein before the step of adjusting the voltage of the gate of the second thin film transistor to a precharge voltage when the first loop circuit is turned on, the method further comprises:
and when a pre-charge signal output by the front-end control chip is received, a first loop between the pre-charge source and the grid electrode of the second thin film transistor and a second loop between the pre-charge source and the light-emitting unit are conducted.
9. An array substrate, comprising: a light emitting unit and a light emitting unit control circuit as claimed in any one of claims 1 to 5.
10. A display panel comprising a light emitting layer, an encapsulation layer, and the array substrate of claim 9, wherein the light emitting layer is disposed between the array substrate and the encapsulation layer.
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| CN115206227B (en) * | 2022-05-18 | 2023-04-07 | 惠科股份有限公司 | Driving circuit of pixel unit and display panel |
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| CN113689833A (en) * | 2021-07-30 | 2021-11-23 | 惠科股份有限公司 | Drive circuit, multistage drive circuit and display panel |
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| KR101298302B1 (en) * | 2006-09-07 | 2013-08-26 | 더 리젠츠 오브 더 유니버시티 오브 미시간 | Organic Light Emitting Diode Display And Driving Method Thereof |
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